Resins curable with actinic energy ray, process for the production thereof, and photocurable and thermosetting resin composition

ABSTRACT

A photocurable and thermosetting resin composition comprises (A) an actinic energy ray-curable resin having at least one structure represented by the following general formula (1), (B) a polymerization initiator, (C) a diluent, and (D) a polyfunctional oxetane compound. The actinic energy ray-curable resin mentioned above can be produced by causing the reaction of (a) a polyfunctional oxetane compound with (b) an unsaturated monocarboxylic acid and the subsequent reaction of (c) a polybasic acid anhydride with a primary hydroxyl group of the resultant modified oxetane resin (a′). 
                 
 
wherein R 1  represents a hydrogen atom or an alkyl group of 1 to 6 carbon atoms, R 2 , R 3  and R 4  independently represent a hydrogen atom, an alkyl group of 1 to 6 carbon atoms, an aryl group, an aralkyl group, a cyano group, a fluorine atom, or a furyl group, and X represents a polybasic acid anhydride residue.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation of Application PCT/JP01/02487, filed Mar. 27,2001, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a novel resin curable with an actinic energyray and a method for the production thereof, more particularly relatesto an actinic energy ray-curable resin which is soluble in an aqueousalkaline solution and capable of producing a film excelling inresistance to heat, electrical insulation properties, etc and a methodfor the production thereof.

This invention further relates to a photocurable and thermosetting resincomposition which can be developed with an aqueous alkaline solution,contains the actinic energy ray-curable resin as mentioned above andhardens promptly by irradiation of an actinic energy ray such as anultraviolet ray or an electron beam or further hardens by heating, moreparticularly relates to a photocurable and thermosetting resincomposition which is excellent in storage stability, capable ofproducing a cured film excelling in resistance to heat, adhesiveness,electrical insulation properties, etc. without causing cracks, andadoptable in various application fields such as a solder resist to beused in the production of printed circuit boards, interlaminarinsulating materials for build-up circuit boards, a plating resist, aphotosensitive dry film, and fluorescent materials in the production ofPDP.

2. Description of the Prior Art

In the soldering process which is carried out in mounting electronicparts on a printed circuit board, a solder resist is used for thepurpose of preventing molten solder from adhering to irrelevant portionsand protecting circuits. In recent years, a developing type solderresist composition which is used to form a pattern by aphotolithographic method is widely adopted. Particularly, with duerespect to the problem of environmental safety and from the viewpoint ofcost, the solder resist composition of the alkali developing type hascome to play the leading role. As a base resin used for these developingtype solder resists, an actinic energy ray-curable resin obtained by thereaction of an epoxy resin with (meth) acrylic acid and the subsequentreaction of an acid anhydride with the resultant hydroxyl group of themodified resin is generally used.

Meanwhile, in consequence of the trend of IC and LSI parts toward highlydense mounting, the necessity of decreasing the width of circuit linesand the intervals between circuits of the printed circuit boards hasbeen finding growing recognition. Besides, since the operating frequencyof these parts to be mounted is enhanced, the heat value released fromthese parts increases accordingly. Therefore, the printed circuit boardtends to require high thermal stability more than desired heretofore. Inthe actinic energy ray-curable resin obtained by using an epoxy resin asa starting raw material, however, since most of the functional groupswhich bond to an acid anhydride are secondary hydroxyl groups, the resinhas the problem of relatively easily suffering the breakage of bondswhen exposed to an increased temperature for a long time and, as result,inducing the possibility of degradation of such properties as insulationproperties and resistance to heat and contamination of circuits due tothe scattering of the decomposed acid anhydride.

In recent years, from the viewpoints of creation of a new organicreaction and its application to the synthesis of macromolecularcompounds, the organic reaction involving the ring opening additionreaction of an oxetane ring which is an ether of four-membered ring hasbeen studied. For example, the addition reaction of an oxetane compoundand an active ester (T. Nishikubo and K. Sato, Chem. Lett., 697 (1992))and the synthesis of polyester having a primary hydroxyl group attachedto a side chain thereof by the polyaddition reaction of a bisoxetane anda dicarboxylic acid (T. Nishikubo, A. Kameyama, and A. Suzuki, Reactive& Functional Polymers, 37, 19 (1998)) have been studied and reported.Further, the polyaddition reaction of a bisoxetane and a bisphenol hasbeen reported recently (T. Nishikubo, A. Kameyama, M. Ito, T. Nakajima,and H. Miyazaki, Journal of Polymer Chemistry, Vol. 37, pp. 2781-2790(1998)) and tetraphenyl phosphonium bromide (TPPB) etc. are used as areaction catalyst. However, these is no article which makes mention ofthe actinic energy ray-curable compositions of the present invention.

In general, a solder resist composition usually contains apolyfunctional epoxy compound having two or more epoxy groups as athermosetting component for the purpose of improving the resistance tosoldering heat.

Since the polyfunctional epoxy compound exhibits high reactivity, thephotocurable and thermosetting resin composition containing thiscompound exhibits unduly short shelf life (useful life) and is liable togain in viscosity prior to being applied to a blank circuit board. As aresult, it is possible to formulate it as the one-package type only withdifficulty. Accordingly, the composition requires to be formulated asthe two-package type consisting of a hardener solution containing apolyfunctional epoxy compound as a main component thereof and a mainagent solution containing a photosensitive prepolymer as a maincomponent thereof and a curing promotor etc. added thereto. This posesthe problem in working properties because it is necessary to mix themimmediately prior to use.

Further, when the photocurable and thermosetting resin compositioncontaining the polyfunctional epoxy compound is formed into a dry film,the shelf life (useful life) of this film becomes short and thepreservation in the refrigerated state at a temperature of not more than0° C. is required. That is to say, it is deficient in shelf stability atroom temperature. Further, this dry film poses the problem in workingproperties because increase of its temperature to room temperature isrequired prior to use thereof.

SUMMARY OF THE INVENTION

An object of the present invention, therefore, is to solve the problemsmentioned above and to provide a novel actinic energy ray-curable resinwhich is soluble in an aqueous alkaline solution and excellent inresistance to heat, thermal stability, etc and a method for theproduction thereof.

Another object of the present invention is to provide an alkalideveloping type photocurable and thermosetting resin composition whichhardens promptly by irradiation of an actinic energy ray such as anultraviolet ray or an electron beam or further hardens by heating,thereby capable of producing a cured film excelling in variousproperties such as resistance to heat, thermal stability, fastness ofadhesion, and electrical insulating properties.

A further objects of the present invention are to provide an alkalideveloping type photocurable and thermosetting resin composition, whichexcels in storage stability, thus is capable of being formulated as aone-package preparation, and is capable of producing a cured filmexcelling in various properties such as resistance to heat, thermalstability, fastness of adhesion, and electrical insulating propertiesand a photosensitive film capable of being stored at room temperature.

To accomplish the objects mentioned above, in accordance with the firstaspect of the present invention, there is provided an actinic energyray-curable resin (A) which is obtained by causing the reaction of (a)an oxetane compound containing at least two oxetane rings (hereinafterreferred to as “polyfunctional oxetane compound”) with (b) anunsaturated monocarboxylic acid and the subsequent reaction of (c) apolybasic acid anhydride with a primary hydroxyl group of the resultantmodified oxetane resin (a′) and has at least one structure representedby the following general formula (1):

wherein R¹ represents a hydrogen atom or an alkyl group of 1 to 6 carbonatoms, R², R³ and R⁴ independently represent a hydrogen atom, an alkylgroup of 1 to 6 carbon atoms, an aryl group, an aralkyl group, a cyanogroup, a fluorine atom, or a furyl group, and X represents a polybasicacid anhydride residue.

In accordance with the second aspect of the present invention, there isprovided a process of producing the aforementioned actinic energyray-curable resin characterized by comprising causing the reaction of(a) an polyfunctional oxetane compound containing at least two oxetanerings with (b) an unsaturated monocarboxylic acid and the subsequentreaction of (c) a polybasic acid anhydride with a primary hydroxyl groupof the resultant modified oxetane resin (a′).

In a preferred embodiment, 0.1 to 1.0 mol of the unsaturatedmonocarboxylic acid (b) is caused to react with one chemical equivalentof the oxetane ring in the polyfunctional oxetane compound (a) and 0.1to 1.0 mol of the polybasic acid anhydride (c) is caused to react withone chemical equivalent of the primary hydroxyl group in the resultantmodified oxetane resin (a′). As the unsaturated monocarboxylic acid (b)mentioned above, acrylic acid and/or methacrylic acid prove to bepreferable.

The actinic energy ray-curable resin (A) of the present invention isexcellent in thermal stability and resistance to heat, is capable ofcausing photo-radical polymerization and further thermally curable byheat radicals owing to the presence of a photopolymerizable unsaturateddouble bond, and further is soluble in an aqueous alkaline solutionowing to the presence of the carboxyl group. The actinic energyray-curable resin as mentioned above can be easily produced according tothe process of the present invention mentioned above.

According to the third aspect of the present invention, there isprovided a curable composition containing the actinic energy ray-curableresin (A) mentioned above as a curing component. A fundamentalembodiment thereof comprises (A) an actinic energy ray-curable resinhaving at least one structure represented by the general formula (1)mentioned above and (B) a polymerization initiator as essentialcomponents. As the polymerization initiator, a photopolymerizationinitiator (photo-radical polymerization initiator) and/or a heat radicalpolymerization initiator may be used.

In a preferred embodiment of the present invention, there is provided aphotocurable and thermosetting resin composition characterized bycomprising (A) an actinic energy ray-curable resin having at least onestructure represented by the general formula (1) mentioned above, (B) apolymerization initiator, (C) a diluent, and (D) a polyfunctionaloxetane compound.

Since the curable composition of the present invention uses as aphotosensitive resin component the actinic energy ray-curable resinmentioned above which excels in thermal stability and resistance to heatand is soluble in an aqueous alkaline solution, it cures promptly byshort-time irradiation of an actinic energy ray and further is thermallycurable by heat radicals. Furthermore, it is possible to develop thecompound with an aqueous alkaline solution after exposure to light.

Further, since the photocurable and thermosetting resin composition ofthe present invention contains a polyfunctional oxetane compound as athermosetting component besides the actinic energy ray-curable resinmentioned above as a photosensitive resin component, it is capable ofbeing formulated as a one package preparation, exhibits longer shelflife (useful life), and is allowed to form a photosensitive dry filmwhich can be stored at room temperature. By the use of the photocurableand thermosetting resin composition of the present invention, it ispossible to obtain a cured product excelling in resistance to cracking,electrical insulation properties, resistance to heat, fastness ofadhesion, resistance to chemicals, etc. without causing any shrinkage onthermal curing carried out after the exposure to light and development.

In accordance with the fourth aspect of the present invention, there isprovided a product manufactured by using the photocurable andthermosetting resin composition mentioned above such as, for example, aprinted circuit board having a solder resist, a multi-layer printedcircuit board having an insulating layer formed between conductorcircuit layers, and a photosensitive dry film having a photosensitivelayer, respectively formed by using the photocurable and thermosettingresin composition mentioned above.

BRIEF DESCRIPTION OF THE DRAWING

The single FIGURE shows the IR spectrum of the resin produced inSynthesis Example 1 to be described hereinafter.

DETAILED DESCRIPTION OF THE INVENTION

The present inventors, after continuing a diligent study to solve theproblems mentioned above, have found that by using a compound containingoxetane rings as a starting raw material instead of an epoxy compoundwhich preponderantly causes a secondary hydroxyl group by the reactionwith an unsaturated monocarboxylic acid, specifically by causing apolyfunctional oxetane compound (a) to react with an unsaturatedmonocarboxylic acid (b) and then further causing a polybasic acidanhydride (c) to react with a primary hydroxyl group of the resultantmodified oxetane resin (a′), there is obtained an actinic energyray-curable resin of which bonding sites suffer the thermal breakageonly with difficulty and which excels in resistance to heat and thermalstability and that the use of this resin allows the preparation of analkali developing type photocurable and thermosetting resin compositionexcelling in resistance to heat and thermal stability.

Specifically, the actinic energy ray-curable resin of the presentinvention is capable of promptly curing by short-time irradiation of anactinic energy ray owing to the structure having a photopolymerizableunsaturated double bond, particularly (meth)acryloyl group, and alsothermally curable by heat radicals owing to the presence of theunsaturated double bond. Further, since the functional group to which apolybasic acid anhydride (c) is bonded is a primary hydroxyl group ofthe modified oxetane resin (a′) caused by the reaction of thepolyfunctional oxetane compound (a) with the unsaturated monocarboxylicacid (b), the resultant resin excels in thermal stability and resistanceto heat. Furthermore, the actinic energy ray-curable resin of thepresent invention has a carboxyl group introduced thereinto by causingthe polybasic acid anhydride (c) to react with the primary hydroxylgroup of the modified oxetane resin (a′), it is soluble in an aqueousalkaline solution. Accordingly, the curable composition containing thisresin as a curing component, particularly the photocurable andthermosetting resin composition cures promptly by short-time irradiationof an actinic energy ray, can be developed with an aqueous alkalinesolution after exposure to light, and allows formation of a cured filmexcelling in various properties such as resistance to heat, fastness ofadhesion, electrical insulating properties, and resistance to chemicalsby the thermal curing of the coating film thereof after exposure tolight and development, without causing any shrinkage on curing.

Now, the actinic energy ray-curable resin of the present invention willbe described below.

The actinic energy ray-curable resin of the present invention isobtained by causing (a) a polyfunctional oxetane compound to react with(b) an unsaturated monocarboxylic acid and subsequently causing (c) apolybasic acid anhydride to react with a primary hydroxyl group of theresultant modified oxetane resin (a′). The reaction processes areillustrated as follows.

The modified oxetane resin (a′) of the reaction intermediate can beproduced by causing the reaction of the polyfunctional oxetane compound(a) with the unsaturated monocarboxylic acid (c) in the presence of asuitable reaction promotor. The polyfunctional oxetane compound (a) tobe used for the above-mentioned reaction is not limited to a particularone insofar as it has at least two oxetane rings in its molecule.

As typical examples of the compound containing two oxetane rings in itsmolecule, bisoxetanes represented by the following general formula (2)may be cited.

In the general formula (2) mentioned above, R¹ represents the samemeaning as mentioned above, and R⁵ represents a bivalent group selectedfrom among linear or branched saturated hydrocarbons of 1 to 12 carbonatoms, linear or branched unsaturated hydrocarbons of 1 to 12 carbonatoms, aromatic hydrocarbons represented by the following formulas (A),(B), (C), (D), and (E), linear or cyclic alkylene groups containing acarbonyl group and represented by the following formulas (F) and (G),and aromatic hydrocarbons containing a carbonyl group and represented bythe following formulas (H) and (I).

wherein R⁶ represents a hydrogen atom, an alkyl group of 1 to 12 carbonatoms, an aryl group, or an aralkyl group, R⁷ represents —O—, —S—,—CH₂—, —NH—, —SO₂—, —CH(CH₃)—, —C(CH₃)₂—, or —C(CF₃)₂—, and R⁸represents a hydrogen atom or an alkyl group of 1 to 6 carbon atoms.

wherein n represents an integer of 1 to 12.

As typical examples of the compound containing three or more oxetanerings in its molecule, etherified products of an oxetane with a hydroxylgroup-containing resin such as a novolak resin, poly(p-hydroxy styrene),cardo type oxetane resin, calixarenes, or a silicone resin like acylseski oxane besides a compound represented by the following generalformula (3) may be cited. In addition thereto, a copolymer of anunsaturated monomer containing an oxetane ring and an alkyl(meth)acrylate may be cited. The term “(meth)acrylate” as used in thepresent specification refers collectively to acrylate and methacrylate.This holds good for other similar expression.

In the general formula (3) mentioned above, R¹ represents the samemeaning as mentioned above, R⁹ represents a residue of the hydroxylgroup-containing resin of the etherified product mentioned above, abranched alkylene group of 1 to 12 carbon atoms represented by thefollowing formula (J), (K) or (L), or an aromatic hydrocarbonrepresented by the following formula (M), (N) or (P), and m representsthe number of functional groups bonded to the residue R⁹, an integer ofthree or more, preferably an integer of 3 to 5,000.

wherein R¹⁰ represents a hydrogen atom, an alkyl group of 1 to 6 carbonatoms, or an aryl group.

As the unsaturated monocarboxylic acid (b) to be used for the reactionmentioned above, a compound containing a polymerizable unsaturated groupand a carboxylic group in combination in its molecule is preferable. Asconcrete examples, acrylic acid, methacrylic acid, cinnamic acid,crotonic acid, sorbic acid, α-cyanocinnamic acid, β-styryl acrylic acid,etc. may be cited. Alternatively, a half ester of a dibasic acidanhydride with a (meth)acrylate having a hydroxyl group may be used. Asconcrete examples, the half esters of the acid anhydride such asphthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, maleicacid, and succinic acid with the hydroxyl group-containing(meth)acrylate such as hydroxyethyl acrylate, hydroxyethyl methacrylate,hydroxypropyl acrylate, and hydroxypropyl methacrylate may be cited.These unsaturated monocarboxylic acids may be used either singly or inthe form of a combination of two or more members.

In the reaction mentioned above, the ratio of the polyfunctional oxetanecompound (a) to the unsaturated monocarboxylic acid (b) (the chargingratio in the reaction mixture) is desired to be such that the ratio ofequivalent weights of oxcetane ring/carboxylic acid is not less than0.1, preferably in the range of 0.3 to 1.0. If the ratio of equivalentweights mentioned above is lower than 0.1, the compound will be at adisadvantage in acquiring insufficient polymerizable groups introducedinto the reaction product and thus an unduly low photo-curing propertiesand, as a result, failing to allow a coating film to have sufficientproperties. Conversely, the ratio of equivalent weights mentioned aboveexceeding 1.0 is not preferable because the unreacted unsaturatedmonocarboxylic acid remains in the resin. When the unsaturatedmonocarboxylic acid remains in the unreacted state, it may be removed bya well known method such as vacuum distillation and alkali cleaning.

When the modified oxetane resin (a′) of a higher molecular weight isneeded, part of the unsaturated monocarboxylic acid (b) to be used forthe reaction may be replaced with a polycarboxylic acid or polyphenol ofbifunctionality or more functionality. Particularly, it is possible toobtain a linear macromolecular compound in the case of the bifunctionalcarboxylic acid or phenol and a branched macromolecular compound in thecase of the trifunctional carboxylic acid or phenol. As concreteexamples of the polycarboxylic acid, bifunctional carboxylic acids suchas succinic acid, adipic acid, muconic acid, suberic acid,tetrahydrophtalic acid, hexahydrophthalic acid, hexahydroisophthalicacid, phtalic acid, isophtalicacid, and terephthalic acid, andtrifunctional carboxylic acids such as 1,2,3-propane tricarboxylic acid,citric acid, aconitic acid, and trimellitic acid may be cited. Asconcrete examples of the polyphenol, bifunctional phenols such ascatechol, resorcin, hydroquinone, 1,4-naphthalene diol, 1,5-naphthalenediol, bisphenol A, and biphenol, and trifunctional phenols such as2,4,4′-trihydroxybenzophenone and 4,4′,4″-methylidene trisphenol may becited.

As a reaction promotor, any compound may be arbitrarily selected fromamong a tertiary amine, a tertiary amine salt, a quaternary onium salt,a tertiary phosphine, a phosphonium ylide, and a crown ether complex.These compounds may be used either singly or in the form of acombination of two or more members.

As the tertiary amine, triethylamine, tributylamine, DBU(1,8-diazabicyclo[5.4.0]undeca-7-ene), DBN(1,5-diazabicyclo[4.3.0]nona-5-ene), DABCO(1,4-diazabicyclo[2.2.2]octane), pyridine, N,N-dimethyl-4-aminopyridine, etc. may be cited.

As the tertiary amine salt, U-CAT series of Sun-Apro K.K., for example,may be cited.

As the quaternary onium salt, ammonium salts, phosphonium salts,arsonium salts, stibonium salts, oxonium salts, sulfonium salts,selenonium salts, stannonium salts, iodonium salts, etc. may be cited.Particularly preferable salts are ammonium salts and phosphonium salts.As concrete examples of the ammonium salts, tetra-n-butylammonium halidesuch as tetra-n-butylammonium chloride (TBAC), tetra-n-butylammoniumbromide (TBAB), and tetra-n-butylammonium iodide (TBAI), andtetra-n-butylammonium acetate (TBAAc) may be cited. As concrete examplesof the phosphonium salts, tetra-n-butylphosphonium halide such astetra-n-butylphosphonium chloride (TBPC), tetra-n-butylphosphoniumbromide (TBPB), and tetra-n-butylphosphonium iodide (TBBI),tertraphenylphosphonium halide such as tetraphenylphosphonium chloride(TPPC), tetraphenylphosphonium bromide (TPPB), andtetraphenylphosphonium iodide (TPPI), and ethyltriphenylphosphoniumbromide (ETPPB), ethyltriphenylphosphonium acetate (ETPPAc), etc. may becited.

As the tertiary phosphine, any trivalent organic phosphorus compoundscontaining an alkyl group of 1 to 12 carbon atoms or an aryl group maybe used. As the concrete examples thereof, triethylphosphine,tributylphosphine, triphenylphosphine, etc. may be cited.

Further, a quaternary onium salt obtained by the addition reaction of atertiary amine or a tertiary phosphine with a carboxylic acid or ahighly acidic phenol may be used as the reaction promotor. They may bein the form of a quaternary salt before adding to the reaction system.Alternatively, they may be individually added to the reaction system soas to form the quaternary salt in the reaction system. As the concreteexamples thereof, tributylamine acetic acid salt obtained fromtributylamine and acetic acid and triphenylphosphine acetic acid saltformed from triphenylphosphine and acetic acid may be cited.

Although any known compounds obtained by the reaction of a phosphoniumsalt and a base may be used as the phosphonium ylide, a highly stablecompound is preferable from the viewpoint of easy handling. As concreteexamples thereof, (formylmethylene)triphenylphosphine,(acetylmethylene)triphenylphosphine,(pivaloylmethylene)triphenylphosphine,(benzoylmethylene)triphenylphosphine,(p-methoxybenzoylmethylene)triphenylphosphine,(p-methylbenzoylmethylene)triphenylphosphine,(p-nitrobenzoylmethylene)triphenylphosphine,(naphthoyl)triphenylphosphine, (methoxycarbonyl)triphenylphosphine,(diacetylmethylene)triphenylphosphine, (acetylcyano)triphenylphosphine,(dicyanomethylene)triphenylphosphine, etc. may be cited.

As concrete examples of the crown ether complex, complexes of crownethers such as 12-crown-4, 15-crown-5, 18-crown-6, dibenzo-18-crown-6,21-crown-7, and 24-crown-8 with alkali metal salts such as lithiumchloride, lithium bromide, lithium iodide, sodium chloride, sodiumbromide, sodium iodide, potassium chloride, potassium bromide, andpotassium iodide may be cited.

The amount of the reaction promotor to be used is preferred to be in therange of 0.1 to 25 mol %, more preferably 0.5 to 20 mol %, mostpreferably 1 to 15 mol %, based on one mol of the oxetanyl group. If theamount of the reaction promotor to be used is less than 0.1 mol % of theoxetanyl group, the reaction will not proceed at a practical reactionspeed. Conversely, a large amount exceeding 25 mol % is not desirablefrom the economical viewpoint because a remarkable reaction promotioneffect will not be obtained even when the promotor is present in such alarge amount.

The reaction temperature is preferred to be in the approximate range of100 to 200° C., more preferably 120 to 160° C. If the reactiontemperature is lower than 100° C., the reaction will not proceed to asatisfactory extent. Conversely, the reaction temperature exceeding 200°C. is not desirable from the reasons that the reaction products willtend to cause the thermal polymerization due to the reaction of thedouble bonds thereof and that the unsaturated monocarboxylic acid havinga low boiling point will evaporate. Although the reaction time may besuitably selected depending on the reactivity of the raw materials to beused and the reaction temperature, the preferred reaction time is about5 to 72 hours.

Next, the reaction of the above resin with a polybasic acid anhydridewill be described below. In accordance with the present invention, theactinic energy ray-curable resin is produced by causing 0.1 to 1.0 molof the polybasic acid anhydride (c) to react with one chemicalequivalent of the primary hydroxyl group of the modified oxetane resin(a′) produced as described above. Since the primary hydroxyl groupcaused by the addition reaction of the oxetane ring with the unsaturatedmonocarboxylic acid is present in the modified oxetane resin (a′) andthe carboxyl group is introduced into the resin by the addition reactionof this hydroxyl group with the polybasic acid anhydride, the resultantresin will be soluble in an aqueous alkaline solution.

As concrete examples of the polybasic acid anhydrides (c), dibasic acidanhydrides such as phthalic anhydride, succinic anhydride,octenylphthalic anhydride, pentadodecenylsuccinic anhydride, maleicanhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride,methyltetrahydrophthalic anhydride, 3,6-endomethylenetetrahydrophthalicanhydride, methylendomethylenetetrahydrophthalic anhydride,tetrabromophthalic anhydride, chlorendic anhydride, and trimelliticanhydride; and tetrabasic acid dianhydrides such asbiphenyl-tertacarboxylic dianhydride, naphthalene-tertacarboxylicdianhydride, diphenyl ether-tertacarboxylic dianhydride,cyclopentane-tertacarboxylic dianhydride, pyromellitic anhydride, andbenzophenone-tetracarboxylic dianhydride may be used. These polybasicacid anhydrides may be used either singly or in the form of acombination of two or more members.

The reaction of the polybasic acid anhydride (c) with the modifiedoxetane resin (a′) may be performed at a temperature in the approximaterange of 50 to 150° C., preferably 80 to 130° C. in a proportion asmentioned above. The amount of the polybasic acid anhydride (c) to beused is preferred to be in the range of 0.1 to 1.0 mol per one chemicalequivalent of the primary hydroxyl group of the modified oxetane resin(a′). The amount of the polybasic acid anhydride lower than 0.1 mol isnot preferable from the reason that the amount of the carboxyl groupsintroduced into the resin is too small and thus sufficientalkali-solubility is not imparted to the resin. Conversely, an undulylarge amount exceeding 1.0 is not preferable because the unreactedunsaturated monocarboxylic acid remains in the resin and it willdeteriorate the properties of the resin such as durability andelectrical insulation properties.

In the reaction of the polybasic acid anhydride (c) with the modifiedoxetane resin (a′) mentioned above, a reaction promotor such as atertiary amine, a tertiary amine salt, a quaternary onium salt, atertiary phosphine, a phosphonium ylide, a crown ether complex, and anadduct of a tertiary amine or a tertiary phosphine with a carboxylicacid or a highly acidic phenol maybe used. The amount of the reactionpromotor to be used is preferred to be in the range of 0.1 to 25 mol %,preferably 0.5 to 20 mol %, most preferably 1 to 15 mol %, of thepolybasic acid anhydride (c). If the catalyst used for the reaction ofthe unsaturated monocarboxylic acid mentioned above still remains in thesystem, however, the reaction will be promoted even if the catalyst isnot newly added.

Although the aforementioned reaction of the polyfunctional oxetanecompound (a) with the unsaturated monocarboxylic acid (b) and thereaction of the modified oxetane resin (a′) with the polybasic acidanhydride (c) proceed either in the presence of an organic solvent or inthe absence of a solvent, the reaction may also be performed in thepresence of a diluent to be described hereinafter for the purpose ofimproving the agitating effect during the reaction. When the organicsolvent is used as the diluent during the synthesis, the solvent mayberemoved by a well-known method such as vacuum distillation.

As the organic solvent, any known organic solvents may be used insofaras they will not exert a harmful influence on the reaction and can keepthe reaction temperature. As concrete examples thereof, alcohols such asdiethylene glycol monomethyl ether, diethylene glycol monoethyl ether,dipropylene glycol monomethyl ether, and dipropylene glycol monobutylether; glycol esters such as ethylene glycol monomethyl ether acetate,diethylene glycol monomethyl ether acetate, diethylene glycol monoethylether acetate, propylene glycol monomethyl ether acetate, anddipropylene glycol monomethyl ether acetate; ethers such as diethyleneglycol dimethyl ether and dipropylene glycol dimethyl ether; ketonessuch as methylisobutyl ketone and cyclohexanone; and aromatichydrocarbons such as toluene and xylene may be cited.

In the aforementioned reaction of the polyfunctional oxetane compound(a) with the unsaturated monocarboxylic acid (b) and the reaction of themodified oxetane resin (a′) with the polybasic acid anhydride (c), airblowing or the addition of a polymerization inhibitor may be done forthe purpose of preventing the reaction mixture from gelation due topolymerization of the unsaturated double bonds. As the examples of thepolymerization inhibitor, hydroquinone, toluquinone, methoxyphenol,phenothiazine, triphenyl antimony, copper chloride, etc. may be cited.

By mixing the actinic energy ray-curable resin (A) obtained by themethod of the present invention with a photo-radical polymerizationinitiator and/or a heat radical polymerization initiator which generateradicals by irradiation of an actinic energy ray or by heating as thepolymerization initiator (B), an actinic energy ray-curable compositionor a photocurable and thermosetting composition may be obtained.Further, by adding a reactive monomer as the diluent (C) to be describedhereinafter to the composition, it is possible to improve thephoto-curing properties thereof. Incidentally, the amount of the actinicenergy ray-curable resin (A) to be incorporated in the curablecomposition of the present invention, particularly the actinic energyray-curable composition is not limited to a particular range.

As the photo-radical polymerization initiator to be used as thepolymerization initiator (B), any known compounds which generateradicals by irradiation of an actinic energy ray may be used. Asconcrete examples thereof, benzoin and alkyl ethers thereof such asbenzoin, benzoin methyl ether, and benzoin ethyl ether; acetophenonessuch as acetophenone, 2,2-dimethoxy-2-phenyl acetophenone and4-(1-t-butyldioxy-1-methylethyl) acetophenone; anthraquinones such as2-methylanthraquinone, 2-amylanthraquinone, 2-t-butyl anthraquinone, and1-chloroanthraquinone; thioxanthones such as 2,4-dimethylthioxanthone,2,4-diisopropylthioxanthone, and 2-chlorothioxanthone; ketals such asacetophenone dimethyl ketal and benzyl dimethyl ketal; benzophenonessuch as benzophenone, 4-(1-t-butyldioxy-1-methylethyl) benzophenone, and3,3′,4,4′-tetrakis(t-butyldioxycarbonyl) benzophenone;aminoacetophenones such as2-methylthio-1-[4-(methylthio)phenyl]-2-morpholino-propane-1-one and2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butane-1-one;alkylphosphines such as 2,4,6-trimethylbenzoyl phosphine oxide; andacryzines such as 9-phenyl acryzine may be cited.

These well-known and widely used photo-radical polymerization initiatorsmay be used either singly or in the form of a combination of two or moremembers. The amount of the photo-radical polymerization initiator to beused is preferred to be in the range of from 0.1 to 30 parts by weight,based on 100 parts by weight of the actinic energy ray-curable resin (A)mentioned above. If the amount of the photo-radical polymerizationinitiator to be used is less than the lower limit of the range mentionedabove, the composition will not be photocured by irradiation of anactinic energy ray or the irradiation time should be prolonged, and acoating film of satisfactory properties will be obtained only withdifficulty. Conversely, even if the photo-radical polymerizationinitiator is added to the composition in a large amount exceeding theupper limit of the range mentioned above, the composition will notattain the further improvement in the curing properties and such a largeamount is not desirable from the economical viewpoint.

In the curable composition, particularly the photocurable andthermosetting composition of the present invention, for the purpose ofimproving the curing with an actinic energy ray, a curing promotorand/or sensitizer may be used in combination with the photo-radicalpolymerization initiator mentioned above. As the curing promoters whichare usable herein, tertiary amines such as triethylamine,triethanolamine, 2-dimethylaminoethanol, N,N-(dimethylamino)ethylbenzoate, N,N-(dimethylamino)isoamyl benzoate, andpentyl-4-dimethylamino benzoate; and thioethers such as β-thiodiglycolmay be cited. As the sensitizer, sensitizing dyestuff such as (keto)cumalin and thioxantene; and alkyl borates of such dyestuff as cyanine,rhodamine, safranine, malachite green, and methylene blue maybe cited.These curing promotors and/or sensitizers may be used independentlyeither singly or in the form of a combination of two or more members.The amount of the curing promoters and/or sensitizers to be used ispreferred to be in the range of from 0.1 to 30 parts by weight, based on100 parts by weight of the actinic energy ray-curable resin (A)mentioned above.

As the heat radical polymerization initiators which are usable in thepresent invention, organic peroxides such as benzoyl peroxide, acetylperoxide, methyl ethyl ketone peroxide, lauroyl peroxide, dicumylperoxide, di-t-butyl peroxide, t-butyl hydroperoxide, and cumenehydroperoxide; and azo type initiators such as2,2′-azobisisobutyronitrile, 2,2′-azobis-2-methylbutyronitrile,2,2′-azobis-2,4-divaleronitrile, 1,1′-azobis(1-acetoxy-1-phenylethane),1′-azobis-1-cyclohexane carbonitrile, dimethyl-2,2′-azobisisobutylate,4,4′-azobis-4-cyanovalic acid, and 2-methyl-2,2′-azobispropanenitrilemay be cited. As the preferred initiator,1,1′-azobis(1-acetoxy-1-phenylethane) of the non-cyane and non-halogentype is cited. The heat radical polymerization initiator is used in therange of 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight,based on 100 parts by weight of the actinic energy ray-curable resin (A)mentioned above.

When an organic peroxide which exhibits a lower curing rate is used asthe heat radical polymerization initiator, tertiary amines such astributylamine, triethylamine, dimethyl-p-toluidine, dimethylaniline,triethanolamine, and diethanolamine, or metallic soap such as cobaltnaphthenate, cobalt octoate, and manganous naphthenate may be used as apromotor.

Further, when the addition reaction of the polyfunctional oxetanecompound (a) with the unsaturated monocarboxylic acid (b) is performedin such a proportion that the ratio of equivalent weight of theunsaturated monocarboxylic acid to that of the oxetanyl group is lessthan 1.0 mol (that is to say, the case that the oxetane ring remains inthe ester compound obtained), the actinic energy ray-curable resin ofthe present invention can be formulated as the radical-cationic hybridcuring system by adding a cationic polymerization initiator whichinitiates the photo-cationic polymerization by irradiation of an actinicenergy ray. Accordingly, it is possible to obtain a cured product byemploying the photo-cationic polymerization in combination the radicalpolymerization. As the cationic polymerization initiator, any of thewell-known cationic polymerization initiators such as diaryl iodoniumsalts, triaryl sulfonium salts, thiobistriaryl sulfonium salts,selenonium salts, and phosphonium salts may be used. These cationicpolymerization initiators may be used either singly or in the form of acombination of two or more members. The amount of the cationicpolymerization initiator to be incorporated in the curable compositionmay be is in the conventionally used range, generally not less than 0.05part by weight, preferably not less than 0.1 part by weight, mostpreferably in the range of 0.5 to 10 parts by weight, based on 100 partsby weight of the actinic energy ray-curable resin (A) mentioned above.

The curable composition, particularly the photocurable and thermosettingcomposition of the present invention may incorporate a diluent therein.As the diluent (C), a compound having a polymerizable group which iscapable of taking part in the curing rection can be used besides anorganic solvent. Any known reactive diluents such as, for example,monofunctional acrylates and/or polyfunctional acrylates can be used. Asconcrete examples thereof, methyl (meth)acrylate, ethyl (meth)acrylate,n-butyl (meth)acrylate, isobutyl (metha)crylate, 2-ethylhexyl(meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl(meth)acrylate, stearyl (meth)acrylate, methoxypolyethylene glycol(meth)acrylate, cyclohexyl (meth)acrylate, tetrahydrofurfuryl(meth)acrylate, isobornyl (meth)acrylate, benzyl (meth)acrylate,2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate,2-hydroxybutyl (meth)acrylate, dimethylaminoethyl (meth) acrylate,ethylene glycol di(meth)acrylate, diethylene qlycol di(meth)acrylate,1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth) acrylate,trimethylol propane tri(meth) acrylate, glycerin di(meth)acrylate,pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate,dipentaerythritol hexa(meth)acrylate, polyester acrylate, reactionproducts of dibasic acid anhydrides with alcohols having one or moreunsaturated groups in its molecule, etc. may be cited. The diluents (c)can be used either singly or in the form of a mixture of two or moremembers and the amount thereof is not limited to a particular range.

Then, the photocurable and thermosetting resin composition of thepresent invention will be described below.

The first characteristic feature of the photocurable and thermosettingresin composition of the present invention resides in the use of thealkali-soluble actinic energy ray-curable resin (A) excelling in thermalstability and resistance to heat as mentioned above and the secondcharacteristic feature in the use of the polyfunctional oxetane compound(D) as a thermosetting component. By using the polyfunctional oxetanecompound (D) as the thermosetting component in combination with theactinic energy ray-curable resin (A), the polymerization initiator (B),and the diluent (C) mentioned above, the resultant photocurable andthermosetting resin composition can be formulated as a one-packagepreparation and excels in shelf life (useful life). When thisphotocurable and thermosetting resin composition is applied to asubstrate to form a film and the coating film of the composition isthermally cured after exposure to light and development, there isobtained a cured film excellent in various properties such as resistanceto heat, fastness of adhesion, and electrical insulating properties,without causing any shrinkage on curing and cracks. Further, the use ofthe photocurable and thermosetting resin composition of the presentinvention allows formation of a photosensitive dry film which can bestored at room temperature.

Specifically, since the photocurable and thermosetting resin compositionof the present invention contains the polyfunctional oxetane compound(D) having oxetanyl groups of a four membered ring which reacts with thecarboxyl groups of the actinic energy ray-curable resin (A) during thestep of thermal curing to cause primary hydroxyl groups predominantly,the resultant cured film is excellent in adhesiveness to a substrate ascompared with that obtained by the composition using a polyfunctionalepoxy compound which causes secondary hydroxyl groups preponderantly bythe reaction with the above resin. Further, since the cured filmcontains a large number of ethylene units after the reaction because ofthe four membered ring, it scarcely suffers volume shrinkage and excelsin toughness. As a result, there is obtained a cured film which exhibitsexcellent resistance to cracking. Furthermore, since the reactivity ofthe polyfunctional oxetane compound is lower than that of thepolyfunctional epoxy compound, the photocurable and thermosetting resincomposition containing the polyfunctional oxetane compound exhibitslonger shelf life (useful life), can be formulated as a one packagepreparation, and allows formation of a photosensitive dry film which canbe stored at room temperature. The use of such a photosensitive dry filmis advantageous in terms of workability. Moreover, another effect offurther improving the insulating reliability may also be attaineddepending on the method for the production of the polyfunctional oxetanecompound.

As the polyfunctional oxetane compounds (D), etherified products of anoxetane with a hydroxyl group-containing resin such as a novolak resin,poly(hydroxystyrene), calixarenes, or a silicone resin like a cylseskioxane besides bisoxetanes having two oxetane rings and represented bythe general formula (2) mentioned above and the compound having threeoxetane rings and represented by the general formula (3) mentionedabove, which are to be used as the starting material of the actinicenergy ray-curable resin (A), may be cited.

The polyfunctional oxetane compounds (D) as mentioned above may be usedeither singly or in the form of a combination of two or more members.Among other oxetane compounds cited above, the finely pulverized oxetaneresins which exhibit sparing solubility in the diluent (C) mentionedabove or a combination of the sparingly soluble oxetane resin and thesoluble oxetane resin prove to be particularly desirable. The amount ofthe polyfunctional oxetane compound (D) mentioned above to beincorporated in the composition as a thermosetting component is desiredto be in the range of 5 to 100 parts by weight, preferably 15 to 60parts by weight, based on 100 parts by weight of the actinic energyray-curable resin (A) mentioned above.

It is also preferable that a curing promotor (E) be incorporated intothe composition together with the polyfunctional oxetane compound (D)mentioned above. As the curing promotor (E), any compound may bearbitrarily selected from among tertiary amines, tertiary amine salts,quaternary onium salts, tertiary phosphines, imidazole derivatives, andcrown ether complex (such as, for example, 18-crown-6/potassiumphenoxide, potassium benzoether, KCl, KBr or ammonium acetate). Thesecompounds may be used either singly or in the form of a combination oftwo or more members. Besides, a phosphonium ylide etc. may be used.

In the photocurable and thermosetting resin composition of the presentinvention, an epoxy compound may be mixed as part of the thermosettingcomponent in a proportion not so large as to adversely affect theeffects of the use of the polyfunctional oxetane compound as thethermosetting component. As the epoxy compound mentioned above, anycompound my be used insofar as it has at least two epoxy groups in itsmolecule. As the examples of the epoxy compound, various well-known andpopularly adopted epoxy compounds such as, for example, glycidyl ethercompounds such as bisphenol A epoxy resin, bisphenol F epoxy resin,bisphenol S epoxy resin, brominated bisphenol A epoxy resin,hydrogenated bisphenol A epoxy resin, biphenol epoxy resin, bixylenolepoxy resin, alicyclic epoxy resin, phenol novolak epoxy resin, cresolnovolak epoxy resin, brominated phenol novolak epoxy resin, and novolakepoxy resin of bisphenol A; glycidyl ester compounds such asterephthalic diglycidyl ester, hexahydrophthalic diglycidyl ester, anddimeric diglycidyl ester; and glycidyl amine compounds such astriglycidyl isocyanurate, N,N,N′,N′-tetraglycidyl methaxylene diamine,N,N,N′,N′-tetraglycidyl bis(aminomethyl)-cyclohexane, and N,N-diglycidylaniline may be used. These epoxy compounds may be used either singly orin the form of a combination of two or more members. Although any epoxycompounds which exhibit sparing solubility or solubility in a diluent(C) to be used may be used as the epoxy compound, the finely pulverizedepoxy compound which exhibits sparing solubility in a diluent and is inthe state of solid or semi-solid at room temperature or a combination ofthis sparingly soluble epoxy compound and the soluble epoxy compoundprove to be particularly desirable from the viewpoint of developabilityetc.

Further, for the purpose of promoting the thermal curing reaction, asmall amount of a well-known epoxy curing promotor such as quaternaryammonium salts, quaternary phosphonium salts, tertiary amines,imidazoles, and dicyandiamide may be used in combination therewith.

The actinic energy ray-curable composition or the photocurable andthermosetting resin composition of the present invention as describedabove may incorporate therein, as desired, a well-known and widely usedfiller such as barium sulfate, silica, talc, clay, and calciumcarbonate, a well-known and widely used coloring pigment such asphthalocyanine blue, phthalocyanine green, titanium oxide, and carbonblack, and various additives such as an anti-foaming agent, anadhesiveness-imparting agent, and a leveling agent.

The actinic energy ray-curable composition or the photocurable andthermosetting resin composition of the present invention obtained asdescribed above is adjusted, when necessary, to a level of viscositysuitable for the coating method by addition of the diluent etc., appliedby a suitable coating method such as a screen printing method, a curtaincoating method, a roll coating method, a dip coating method, and a spincoating method to a substrate of a printed circuit board, and thenpredried at a temperature in the approximate range of 60 to 120° C., forexample, thereby to evaporate the organic solvent from the compositionand give rise to a coating film. Thereafter, the composition coated onthe substrate is selectively exposed to an actinic energy ray through aphotomask having a prescribed exposure pattern and the composition inthe unexposed areas of the coating film is developed with an aqueousalkaline solution to obtain a resist pattern.

When the composition is also used as a material for the interlaminarinsulating layer in a build-up multi-layer printed circuit board, apattern may be formed in the same manner as mentioned above.

In the case of the photocurable and thermosetting resin compositioncontaining a thermosetting component, the resist film formed in themanner mentioned above is further thermally cured by subjecting to theheat treatment at a temperature in the approximate range of 100 to 200°C. for about 30 to 60 minutes for the purpose of improving theproperties. By this thermal treatment, in addition to the curingreaction of the aforementiond thermosetting components, thepolymerization of the photocurable resin components is promoted and thecopolymerization of this component with the thermosetting component arealso facilitated so that the consequently produced resist film acquiresimprovements in various properties such as resistance to heat,resistance to adhesion of solder, resistance to solvents, resistance toacids, adhesiveness, resistance to electroless gold plating, electricproperties, printability, and hardness.

In the manufacture of a photosensitive dry film, the photocurable andthermosetting resin composition of the present invention as mentionedabove is adjusted, when necessary, to a level of viscosity suitable forthe coating method, applied to a suitable supporting film such as, forexample, a flexible base film, and then dried at a temperature in theapproximate range of 60 to 100° C., for example, thereby to evaporatethe organic solvent from the composition and give rise to a tack-freephotocurable and thermosetting dry film (photosensitive film). It ispreferred to preserve the photosensitive film formed on the base filmuntil use thereof in such a state that the photosensitive film isprotected by a cover film laminated thereon.

As the base film, various synthetic resin films made of, for example,polyethylene terephthalate (PET), polyethylene (PE), polypropylene,polycarbonate, polyether sulfone, or polyvinyl chloride may be used Theproper thickness of the base film is in the range of 15 to 125 μm.

For the formation of a coating film, various coating methods using anapplicator, a bar coater, a roll coater, a die coater, a curtain flowcoater, a spin coater, etc. or the screen printing method and the likemay be adopted. The proper thickness of the coating film is in the rangeof 10 to 150 μm as the thickness after drying.

The cover film to be laminated on the photosensitive film is used forstably protecting the photosensitive film at the time of not putting touse and removed at the time of use. Therefore, it should have suchproper release characteristics that it is not peeled off at the time ofnot putting to use, but it can be easily separated from thephotosensitive film at the time of use. As the cover film which fulfillssuch requirements, a PET film, a polypropylene film, a PE film, etc. maybe used. Further, the above-mentioned film further coated with siliconeor baked may be used. This cover film is preferred to have a thicknessin the range of about 15 to 100 μm.

Moreover, for the purpose of preventing the photocurable andthermosetting resin composition from suffering the sensitivity reductionowing to oxygen and adhesion of the photomask for pattern formation tobe tightly laminated thereon at the time of exposure, it is possible tofurther form a layer of a water-soluble resin composition on thephotosensitive film. In the case of such a photosensitive film, it ispreserved by laminating the cover film on the layer of the water-solubleresin composition. The layer of the water-soluble resin composition isformed by applying an aqueous 5-20 wt. % solution of polyvinyl alcoholor partially saponified polyvinyl acetate to the photosensitive film insuch a proportion that the thickness may become 1-10 μm as the dry filmthickness and drying it.

Incidentally, ethylene glycol, propylene glycol, polyethylene glycol,etc. may also be added to the solution of the water-soluble resincomposition. In the preparation of this solution, when taking theviscosity and anti-foaming properties thereof into consideration, asolvent such as, for example, methanol, ethylene glycol monomethyl etheracetate, and acetone or a commercially available water-solubleanti-foaming agent or the like may also be added thereto.

In the formation of a coating film on a substrate to be processed, firstthe base film is separated from the photosensitive film and thephotosensitive film is transferred to the substrate to be processed. Asthe transferring method, a hot press bonding method which comprisespreviously heating the substrate to be processed is desirable. A vacuumbonding method which achieves press boding under vacuum may also beadopted. Although the substrate to be processed can be arbitrarilychosen according to the usage of the photosensitive film aimed at. Whenit is used as a solder resist for a printed circuit board, for example,it is transferred to the printed circuit board having circuitspreviously formed thereon. When it is used as an interlaminar insulatinglayer for a build-up multi-layer printed circuit board, it istransferred to an inner board. Thereafter, in the case of the formationof a solder resist, the photosensitive film is selectively exposed to anactinic ray through a photomask having a prescribed pattern by a contactexposure method or non-contact exposure method and the unexposed areasof the film is removed by development with a dilute aqueous alkalinesolution to form a resist pattern. Then, the film is further thermallycured by subjecting to the heat treatment at a temperature in the rangeof about 140 to 200° C., for example.

As an aqueous alkaline solution to be used in the process of developmentmentioned above, aqueous alkaline solutions of sodium hydroxide,potassium hydroxide, sodium carbonate, potassium carbonate, sodiumsilicate, ammonia, organic amines, tetramethylammonium hydroxide, etc.can be used.the concentration of an alkali in the developing solutionmay be proper generally in the range of 0.1 to 5.0 wt. %. As thedeveloping method, various known methods such as dipping development,paddling development, and spraying development may be adopted.

The light sources which are properly used for the purpose ofphoto-curing the actinic energy ray-curable composition or thephotocurable and thermosetting resin composition include a low-pressuremercury lamp, a medium-pressure mercury lamp, a high-pressure mercurylamp, an ultra-high-pressure mercury lamp, a xenon lamp, and a metalhalide lamp, for example. Laser beams may also be utilized as theactinic ray for exposure. Further, electron beams, α-rays, β-rays,γ-rays, X-rays, neutron beams, etc. may be utilized.

Now, the present invention will be described more specifically belowwith reference to working examples. It should be noted, however, thatthe following Examples are intended to be merely illustrative of and inany sense restrictive of the present invention. Wherever the terms“parts” and “%” are used hereinbelow, they invariably refer to thosebased on weight unless otherwise specified.

EXAMPLES OF SYNTHESES OF ACTINIC ENERGY RAY-CURABLE RESIN SynthesisExample 1

Into a 200 ml four-necked flask equipped with a stirrer, a refluxcondenser, and a thermometer, 36.2 g (0.1 mol) of terephthalatebisoxetane (manufactured by Ube Kosan K. K.), 17.2 g (0.2 mol) ofmethacrylic acid, 2.1 g (0.005 mol) of tetraphenylphosphoniumbromide,and 0.1 g of methoquinone were charged and stirred with a magnet stirrerat 140° C. for 12 hours. After the decrease in absorption caused by theoxetane ring at 980 cm⁻¹ has been confirmed by IR spectrum and thereduction of the acid value to a level of not more than 20 mg KOH/g hasbeen also confirmed, the temperature of the reaction mixture was loweredto 100° C. and then 18.0 g (0.18 mol) of succinic anhydride was added tothe mixture. The mixture was further stirred at 100° C. for 3 hours. Theproduct obtained had an acid value of 157 mg KOH/g.

The IR spectrum of the resin obtained is shown in the FIGURE. It can beconfirmed by the IR spectrum shown in the FIGURE that the absorption ofthe primary hydroxyl group and the acid anhydride disappeared and thebroad absorption originated from the carboxyl group appeared. Therefore,it is confirmed that the ring opening addition of the acid anhydride tothe modified oxetane resin was performed and the carboxyl groups wereintroduced into the resin. The resultant product was soluble in anaqueous 1% sodium carbonate solution.

Synthesis Example 2

Into a 200 ml four-necked flask equipped with a stirrer, a refluxcondenser, and a thermometer, 33.4 g (0.1 mol) of xylylene bisoxetane(manufactured by Toa Gosei K.K., product name “XDO”), 17.2 g (0.2 mol)of methacrylic acid, 2.1 g (0.005 mol) of tetraphenylphosphoniumbromide, and 0.1 g of methoquinone were charged and stirred at 130° C.for 24 hours. After the reduction of the acid value to a level of notmore than 20 mg KOH/g has been confirmed, the temperature of thereaction mixture was lowered to 100° C. and then 18.0 g (0.18 mol) ofsuccinic anhydride was added to the mixture. The mixture was furtherstirred at 100° C. for 3 hours. The product obtained had an acid valueof 147 mg KOH/g. The resultant product was soluble in an aqueous 1%sodium carbonate solution.

Synthesis Example 3

The synthesis was carried out by following the procedure of SynthesisExample 1, except that 27.4 g (0.18 mol) of tetrahydrophthalic anhydridewas used in place of the acid anhydride. The product obtained had anacid value of 125 mg KOH/g. As a result of the measurement of IRspectrum of the product, the decrease in absorption caused by theoxetane ring at 980 cm⁻¹ was found and the broad absorption originatedfrom the carboxyl group appeared. Therefore, it has been confirmed thatthe reaction aimed at proceeded properly. The resultant product wassoluble in an aqueous 1% sodium carbonate solution. Hereinafter, thisresin solution will be referred to as varnish “a”.

Synthesis Example 4

The synthesis was carried out by following the procedure of SynthesisExample 2, except that 27.4 g (0.18 mol) of tetrahydrophthalic anhydridewas used in place of the acid anhydride. The product obtained had anacid value of 147 mg KOH/g. As a result of the measurement of IRspectrum of the product, the decrease in absorption caused by theoxetane ring at 980 cm⁻¹ was found and the broad absorption originatedfrom the carboxyl group appeared. Therefore, it has been confirmed thatthe reaction aimed at proceeded properly. The resultant product wassoluble in an aqueous 1% sodium carbonate solution. Hereinafter, thisresin solution will be referred to as varnish “b”.

Synthesis Example 5

Into a 200 ml four-necked flask equipped with a stirrer, a refluxcondenser, and a thermometer, 20.4 g of phenol novolak type oxetane(number of nuclei=7), 8.6 g of methacrylic acid, 2.1 g oftetraphenylphosphonium bromide, 30 g of propylene glycol monomethylether acetate, and 0.1 g of methoquinone were charged and stirred at140° C. for 24 hours. The temperature was lowered to 100° C. and then9.2 g of tetrahydrophthalic anhydride was added to the mixture. Themixture was further stirred for 3 hours to obtain a resin solutioncontaining 54% of actinic energy ray-curable resin. The resin solutionobtained had an acid value of a solid content of 84 mg KOH/gHereinafter, this resin solution will be referred to as varnish “c”.

Synthesis Example 6

A mixture of 50.1 g of methyl methacrylate, 92.1 g of(3-ethyl-3-oxetanyl)methyl methacrylate, and 4.9 g ofazobisisobutyronitrile was added dropwise to 142.2 g of propylene glycolmonomethyl ether acetate heated to 80° C. in advance over a period of 2hours and stirred at the same temperature for 8 hours to synthesize anoxetane ring-containing copolymeric resin. The number-average molecularweight of the copolymer determined by GPC was 12, 000. To this resinsolution, 44.5 g of methacrylic acid, 5.2 g oftetraphenylphosphoniumbromide, and 0.4 g of methoquinone were added andthe resultant mixture was stirred at 140° C. for 12 hours. Thetemperature was lowered to 100° C. and then 60.8 g of tetrahydrophthalicanhydride was added to the mixture. The mixture was further stirred at100° C. for 3 hours to obtain the actinic energy ray-curable resinsolution having an acid value of a solid content of 91 mg KOH/g. Theresultant product was soluble in an aqueous 1% sodium carbonatesolution. Hereinafter, this resin solution will be referred to asvarnish “d”.

Comparative Synthesis Example

Into a four-necked flask equipped with a stirrer and a reflux condenser,220 g of cresol novolak type epoxy resin, “EPICLON N-695” (manufacturedby Dainippon Ink and Chemicals Inc., epoxy equivalent: 220) was chargedand then 220 g of carbitol acetate was added thereto and they weremolten by heating. Then, 0.46 g of hydroquinone as a polymerizationinhibitor and 1.38 g of triphenylphosphine as a reaction catalyst wereadded there to. The resultant mixture was heated to 95-105° C., 72 g ofacrylic acid was gradually added dropwise thereto, and they were leftreacting for 16 hours. The resultant reaction product was cooled to80-90° C., 106 g of tetrahydrophthalic anhydride was added thereto, andthe mixture was left reacting for 8 hours and cooled, and then thereaction product was extracted therefrom.

The carboxyl group-containing photosensitive resin obtained as describedabove had a nonvolatile content of 64% and an acid value of a solidcontent of 97 mg KOH/g. Hereinafter, this reaction solution will bereferred to as varnish “e”.

EXAMPLES OF PHOTOCURABLE AND THERMOSETTING RESIN COMPOSITION

The raw materials used in the following working examples and comparativeexamples are shown in Table 1.

TABLE 1 Components Chemical name or product name Main agentPhotosensitive Varnish “a” obtained in Synthesis prepolymer Example 3Varnish “b” obtained in Synthesis Example 4 Varnish “c” obtained inSynthesis Example 5 Varnish “d” obtained in Synthesis Example 6 Varnish“e” obtained in Comparative Synthesis Example Filler SilicaPhotopolymerization 2-Methyl-1-[4-(methylthio)phenyl]-2- initiatormorphorino-propan-1-one Coloring pigment Phthalocyanine green Curing ATetraphenyl phosphonium bromide promotor b Imidazol Diluent Dipropyleneglycol monomethyl ether Silicone-based KS-66 (manufactured by Shinetsuanti-foaming agent Chemical Industries Co., Ltd.) AdditiveOrganobentonite Hardener Photopolymerizable Dipentaerythritolhexaacrylate monomer Epoxy resin TEPIC (manufactured by Nissan ChemicalIndustries Ltd.) Oxetane resin Terephthalate bisoxetane (manufactured byUbe Kosan K. K.) Diluent Dipropylene glycol monomethyl ether

Examples 1-4 and Comparative Example

The main agent solution of each of the examples shown in Table 2 wasprepared by compounding relevant components at proportions showncorrespondingly in the same table and kneading them with a three-rollmill. The hardener solution of the same example was prepared similarlyby compounding relevant components at proportions shown in Table 2 andkneading them with the tree-roll mill. The photocurable andthermosetting resin compositions thus obtained in two liquid state werechanged to one liquid state by mixing them and subjected to thefollowing evaluation.

TABLE 2 Examples Comp. Components and amounts (parts) 1 2 3 4 ExampleMain Varnish a 100 — — — — agent (solid b — 100 — — — (content c — — 100— — d — — — 100 — e — — — — 100 Filler 30 30 30 30 30Photopolymerization 10 10 10 10 10 initiator Coloring pigment 1 1 1 1 1Curing a 3.5 3.5 3.5 3.5 — promoter b — — — — 0.5 Diluent 10 10 10 10 10Silicone-based 1 1 1 1 1 anti-foaming agent Additive 5 5 5 5 5 HardenerPhotopolymerizable 20 20 20 20 20 monomer Epoxy resin — — — — 30 Oxetaneresin 30 30 30 30 — Diluent 5 5 5 5 5Evaluation of Quality:

(1) Storage Stability

The photocurable and thermosetting resin compositions prepared asdescribed above in one liquid state was left standing at 50° C. for oneweek and their state at the end of the standing were examined toevaluate the storage stability. As a result, the resin composition ofComparative Example has solidified. On the contrary, the resincompositions of Examples 1 to 4 have maintained their liquid statewithout causing gelation. To be specific, this means that the resincompositions according to Examples 1-4 of the present invention excel instorage stability and can be formulated as a one package preparatin.

(2) Developability

The photocurable and thermosetting resin compositions obtained inExamples 1-4 which could keep the liquid state without causing gelationin the test for storage stability were each applied by the screenprinting method onto the entire surface of a copper-clad substrate andthen dried by heating at 80° C. for 30 minutes. Each substrate wasentirely exposed to light through a negative film with a prescribedexposure dose and then developed with an aqueous 1 wt % Na₂CO₃ solutionused as a developing solution under the condition of a spraying pressureof 2 kg/cm² for one minute to form a resist pattern thereon. Thedevelopability was visually examined through a microscope and rated onthe following criterion.

⊚: Complete development even in very small portions

∘: Presence of thin undeveloped portions in the substrate surface

Δ: Remarkable presence of undeveloped portions

X: Almost no development

(3) Adhesiveness:

The photocurable and thermosetting resin compositions obtained inExamples 1-4 which could keep the liquid state without causing gelationin the test for storage stability were each applied by the screenprinting method onto the entire surface of a printed circuit boardhaving a prescribed pattern formed in advance thereon to form a coatingfilm of about 20 μm tickness. Then, a resin pattern was formed under thesame conditions as in the test for developability in item (2) mentionedabove. The resultant substrate was thermally cured at 180° C. for onehour to prepare a test substrate. This test substrate was incised likecross-cut in the shape of squares in a go board and then subjected to apeel test with a cellophane adhesive tape in accordance with the methodspecified in JIS D-0202 to determine the degree of separation of theresist layer based on the following criterion.

⊚: 100/100 and absolutely no peeling of the resist layer

∘: 100/100, but slight peeling in cross-cut portions

Δ: 50/100-90/100

X: 0/100-50/100

(4) Resistance to Cracking

Test substrates were prepared under the same conditions as in the testfor adhesiveness in item (3) mentioned above by using the photocurableand thermosetting resin compositions obtained in Examples 1-4 whichcould keep the liquid state without causing gelation in the test forstorage stability. These test substrates were subjected to the heatcycle test under the conditions of 1,000 cycles between 125° C.×30minutes and −55° C.×30 minutes to investigate the occurrence of cracks.

(5) Resistance to Soldering Heat

Test substrates were prepared under the same conditions as in the testfor adhesiveness in item (3) mentioned above by using the photocurableand thermosetting resin compositions obtained in Examples 1-4 whichcould keep the liquid state without causing gelation in the test forstorage stability. Each of the test substrates was coated with a rosintype flux, immersed for 30 seconds in a solder bath set in advance at260° C., then rinsed with isopropyl alcohol to remove the fluxtherefrom, and visually examined to find the extents of swelling,separation, and discoloration consequently produced in the resist layeron the test substrate.

⊚: Perfect absence of any discernible change was found.

∘: Slight change was found.

Δ: Swelling or separation of a coating film was not more than 20%.

X: Swelling or separation of a coating film was not less than 20%.

The results of the above tests are collectively shown in Table 3.

TABLE 3 Examples Properties 1 2 3 4 Developability ⊚ ⊚ ◯ ⊚ Adhesiveness⊚ ◯ ⊚ ⊚ Resistance to cracking No No No No cracks cracks cracks cracksResistance to soldering heat ⊚ ◯ ⊚ ⊚

As being clear from the results shown in Table 3, the photocurable andthermosetting resin compositions of the present invention obtained inExamples 1-4 excelled in storage stability as compared with theconventional composition, were developable with an alkali solution, andexhibited good photo-curing properties. Further, it has been confirmedthat cured films excelling in resistance to heat and resistance tocracking can be obtained after the subsequent thermal curing reaction.Incidentally, the insulation resistance measured was the same results asthat obtained by the conventional cured film.

As described above, the actinic energy ray-curable resin of the presentinvention excels in thermal stability and resistance to heat and issoluble in an aqueous alkaline solution. Accordingly, the actinic energyray-curable composition containing this resin as a curing component,particularly the photocurable and thermosetting resin compositioncontaining this resin together with a polyfunctional oxetane compound asa thermosetting component excels in storage stability, cures promptly byshort-time irradiation of an actinic energy ray, can be developed withan aqueous alkaline solution after exposure to light, and allowsformation of a cured film excelling in various properties such aselectrical insulating properties, resistance to heat, fastness ofadhesion, and resistance to chemicals by the thermal curing of thecoating film thereof after exposure to light and development, withoutcausing any shrinkage on curing. It is therefore useful in varioustechnical field as the materials of solder resists and etching resiststo be used for the production of printed circuit boards, interlaminarinsulating materials for build-up boards, plating resists, thephotosensitive dry films, the production of fluorescent materials for DFand PDP, and the like.

While certain specific working examples have been disclosed herein, theinvention may be embodied in other specific forms without departing fromthe spirit or essential characteristics thereof. The described examplesare therefore to be considered in all respects as illustrative and notrestrictive, the scope of the invention being indicated by the appendedclaims rather than by the foregoing description and all changes whichcome within the meaning and range of equivalency of the claims are,therefore, intended to be embraced therein.

1. A curable composition, characterized by comprising (A) an actinicenergy ray-curable resin which is obtained by causing the reaction of(a) an oxetane compound containing at least two oxetane rings with (b)an unsaturated monocarboxylic acid and the subsequent reaction of (c) apolybasic acid anhydride with a primary hydroxyl group of the resultantmodified oxetane resin (a′) and has at least one structure representedby the following general formula (1) and (B) a polymerization initiator.

wherein R¹ represents a hydrogen atom or an alkyl group of 1 to 6 carbonatoms, R², R³ and R⁴ independently represent a hydrogen atom, an alkylgroup of 1 to 6 carbon atoms, an aryl group, an aralkyl group, a cyanogroup, a fluorine atom, or a furyl group, and X represents a polybasicacid anhydride residue.
 2. The composition according to claim 1, whereinsaid actinic energy ray-curable resin (A) is a resin obtained by causing0.1 to 1.0 mol of a unsaturated monocarboxylic acid (b) to react withone chemical equivalent of an oxetane ring in a polyfunctional oxetanecompound (a) containing at least two oxetane rings and subsequentlycausing 0.1 to 1.0 mol of a polybasic acid anhydride (c) to react withone chemical equivalent of a primary hydroxyl group in the resultantmodified oxetane resin (a′).
 3. The composition according to claim 1,wherein said polymerization initiator (B) is a photo-radicalpolymerization initiator and/or a heat radical polymerization initiator.4. A photocurable and thermosetting resin composition, characterized bycomprising (A) an actinic energy ray-curable resin having at least onestructure represented by the following general formula (1), (B) apolymerization initiator, (C) a diluent, and (D) an oxetane compoundcontaining at least two oxetane rings in its molecule

wherein R¹ represents a hydrogen atom or an alkyl group of 1 to 6 carbonatoms, R², R³ and R⁴ independently represent a hydrogen atom, an alkylgroup of 1 to 6 carbon atoms, an aryl group, an aralkyl group, a cyanogroup, a fluorine atom, or a furyl group, and X represents a polybasicacid anhydride residue.
 5. The composition according to claim 4, whereinsaid actinic energy ray-curable resin (A) is a resin obtained by causing0.1 to 1.0 mol of a unsaturated monocarboxylic acid (b) to react withone chemical equivalent of an oxetane ring in a polyfunctional oxetanecompound (a) containing at least two oxetane rings and subsequentlycausing 0.1 to 1.0 mol of a polybasic acid anhydride (c) to react withone chemical equivalent of a primary hydroxyl group in the resultantmodified oxetane resin (a′).
 6. The composition according to claim 5,wherein said unsaturated monocarboxylic acid (b) is acrylic acid and/ormethacrylic acid.
 7. The composition according to claim 4, wherein saidpolymerization initiator (B) is a photo-radical polymerization initiatorand/or a heat radical polymerization initiator.
 8. The compositionaccording to claim 4, wherein said diluent (C) is an organic solventand/or a polyfunctional polymerizable monomer.
 9. The compositionaccording to claim 4, wherein said oxetane compound (D) is a bisoxetanecompound represented by the following general formula (2):

wherein, R¹ represents a hydrogen atom or an alkyl group of 1 to 6carbon atoms, and R⁵ represents a bivalent group selected from amonglinear or branched saturated hydrocarbons of 1 to 12 carbon atoms,linear or branched unsaturated hydrocarbons of 1 to 12 carbon atoms,aromatic hydrocarbons represented by the following formulas (A), (B),(C), (D), and (E):

wherein R⁶ represents a hydrogen atom, an alkyl group of 1 to 12 carbonatoms, an aryl group, or an aralkyl group, R⁷ represents —O—, —S—,—CH₂—, —NH—, —SO₂—, —CH(CH₃)—, —C(CH₃)₂—, or —C(CF₃)₂—, and R⁸represents a hydrogen atom or an alkyl group of 1 to 6 carbon atoms,linear or cyclic alkylene groups containing a carbonyl group andrepresented by the following formulas (F) and (G):

wherein n represents an integer of 1 to 12, and aromatic hydrocarbonscontaining a carbonyl group and represented by the following formulas(H) and (I):


10. The composition according to claim 4, wherein said oxetane compound(D) is a polyfunctional oxetane compound represented by the followinggeneral formula (3):

wherein, m represents the number of functional groups bonded to theresidue R⁹, an integer of three or more, R¹ represents a hydrogen atomor an alkyl group of 1 to 6 carbon atoms, R⁹ represents a residue of anetherified product with oxetane, said residue being a novolak resinresidue, a poly(hydroxy styrene) residue, a calixarene residue, or asilicone resin residue, a branched alkylene group of 1 to 12 carbonatoms represented by the following formula (J), (K) or (L):

or an aromatic hydrocarbon represented by the following formula (M), (N)or (P):

wherein R¹⁰ represents a hydrogen atom, an alkyl group of 1 to 6 carbonatoms, or an aryl group.
 11. The composition according to claim 4,further comprising a curing promoter.